Somebody makes a snap-on lid ring that has both a grommet to seal the snap part, and a threaded cap that screws into it (also with an grommet seal.) Gamma, I think the brand name is (at least on this side of the pond.) The Gamma seals aren't all that cheap though.

I suspect you'd want the down-line attachment to be external (rather than drilling through the bucket) to preserve the watertightness.

jky

How about just a piece of wood with speaker and battery on top of the inner tube, with a couple of straps for the downline? A cloth cover if you need visibility (do a web search for "free-diving float".) Should be easy enough to waterproof your electronics.

What size boats? Risk of being hit? What size course(distance between marks)? Why only 3? Even with an Olympic triangle you need to think of pin end marks etc. What is the purpose of the speaker (you have me intrigued!) The inflatables - did they have speakers? Ground tackle? Permanent or placed each day? Battery charged in situ? Speaker - sound source?

Not used these for sailing but used these for rowing races, should still work

Made out of 2m long 100mm brown draining pipe and a couple of 2lt milk cartons.

Cut bottom out of both the milk cartons. Put one of the cartons over one end of the drainage pipe make small hole in the milk carton screw top and feed rope for mooring the buoy through the hole and up the inside of the drainage pipe. Mix up a few kg of cement and put it down inside the pipe filling the milk carton and the bottom end of the pipe. Once the cement has gone off and plugged the pipe end, put the buoy in the water and fill with water until you have about 1m above water (or whatever height you want). When filling with water measure how much you are adding and once you get them floating at the height you want you then know how much more weight you need to add. Empty the water, you can then workout how much more cement to add into the pipe, once added you can cover the top with the other milk carton to seal the end with duct tape with your battery etc inside in case it gets knocked over. You can also paint these so that are more visible.

They are used for blind sailing training events, and the speakers emit a siren pulse every few seconds so that the sailers can find the marks to round.

The speakers and electronics are all sorted it's just the bit of making them float at the moment, previous trips we have used spare RIBs, kayaks or what ever we have to hand - so it would be nice to get something permanent.

The sailing boats change depending on what's available for training or what the sailors need to work on - from keel boats to dinghy - but this is match racing so only two boats per race

The course is start line and windward then the start becomes a gate - we don't use a pin end / committee boat for training as no one wants to sit with the siren going all day.

We do have a small risk of the marks getting hit, as with any sailing event they always try and push it.

The distance between marks can vary as with any race - but ideally they are far enough apart so the sailors have to feel the wind upwind until they can find the sound - but the sirens are very loud and uncomfortable to listen.

The marks would be retrieved after each day, and the mark aspect stay at the local training area and the electronics removed for charging and security.

The marks would be retrieved after each day, and the mark aspect stay at the local training area and the electronics removed for charging and security.

Any sense in leaving the electronics in situ and wiring in a charging circuit rather than removing the electronics and battery each time?

Any issues with storage space? (buckets / barels that stack would be easier to pack away into a car or cupboard than 2m long bits of pipe).

Given the particular application I wonder if you can't find a local place to sponsor your marks? It sounds like the sort of thing that will attract attention (therefore marketing benefit!) and where there is a feel good factor about being associated with it...

Once you've faffed about with attaching bits and bobs to buckets and plumbing the electrics etc you might find that inflatable marks are not much more?

They are used for blind sailing training events, and the speakers emit a siren pulse every few seconds so that the sailers can find the marks to round.

OK Makes sense - was imagining it was speaking and needed to be audible - but it just needs to make a noise that makes sense.

But does the size of the mark matter... i.e. is the idea that everyone uses feel and hearing to navigate or are better sighted sailors expected to use sight too...? My point being that a 2m x 1.5m orange inflatable is a bit bigger and easier to see than a gallon bucket.

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The speakers and electronics are all sorted it's just the bit of making them float at the moment

How did you secure to the inflatables?

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The sailing boats change depending on what's available for training or what the sailors need to work on - from keel boats to dinghy - but this is match racing so only two boats per race

but exponentially more aggressive sailing! Your mark is getting dinged! So does the mark construction need to protect the speaker and electrics
security.

Getting your bucket to float with some weight in it will be easy and no reason the battery can't be inside. Speaker inside or outside? Again easy enough and you can get some gromits that let you cable out.

I'd consider doing as poly suggests - fixed mount the electrics and plug in the mark.

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Originally Posted by Poly

Any issues with storage space? (buckets / barels that stack would be easier to pack away into a car or cupboard than 2m long bits of pipe).

2m pipe will be easy if you have a 2.5m high cupboard or somewhere to lie them down ;-)

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Once you've faffed about with attaching bits and bobs to buckets and plumbing the electrics etc you might find that inflatable marks are not much more?

Erm... the cheapest I've ever seen an inflatable is £60 from Lomo. But if you wanted huge you can make that £250-£600! And you still need the electrics to do something with...

OK ignoring the electronics issues - the biggest challenge with a mark is you need some from of hoop underneath it to attach ground tackle to. We have '45gal' plastic drums with an inbuilt eye that you can shackle tackle to. They were there for lifting and we use the drum upside down but we can't find those anymore. You can drill an eye through but maintaining a seal is tricky... If anyone has found a reliable way please post!

Erm... the cheapest I've ever seen an inflatable is £60 from Lomo. We have '45gal' plastic drums with an inbuilt eye that you can shackle tackle to. They were there for lifting and we use the drum upside down but we can't find those anymore. You can drill an eye through but maintaining a seal is tricky... If anyone has found a reliable way please post!

Plastic Drums etc will take almost as much abuse as your fake inflatable though, compared to inflatable marks which then get dragged across concrete floors because they are awkward to carry and so get damaged and need replaced... So may be long term advantage.

Anchor down and use a length of bungee cord to the barrel that will compensate for rise and fall of tide etc and always under tension length dependant on on water depth and how accurate you want the position.